2 * Copyright (C) 1990 Free Software Foundation, Inc.
4 * This program is free software; you can redistribute it and/or modify it
7 * This program is distributed in the hope that it will be useful, but WITHOUT
8 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
9 * FITNESS FOR A PARTICULAR PURPOSE.
11 * backupfile.c -- make Emacs style backup file names
13 * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
15 * $OpenBSD: backupfile.c,v 1.20 2009/10/27 23:59:41 deraadt Exp $
26 #include "backupfile.h"
29 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
31 /* Which type of backup file names are generated. */
32 enum backup_type backup_type = none;
35 * The extension added to file names to produce a simple (as opposed to
36 * numbered) backup file name.
38 const char *simple_backup_suffix = "~";
40 static char *concat(const char *, const char *);
41 static char *make_version_name(const char *, int);
42 static int max_backup_version(const char *, const char *);
43 static int version_number(const char *, const char *, size_t);
44 static int argmatch(const char *, const char **);
45 static void invalid_arg(const char *, const char *, int);
48 * Return the name of the new backup file for file FILE, allocated with
49 * malloc. Return 0 if out of memory. FILE must not end with a '/' unless it
50 * is the root directory. Do not call this function if backup_type == none.
53 find_backup_file_name(const char *file)
55 char *dir, *base_versions, *tmp_file;
58 if (backup_type == simple)
59 return concat(file, simple_backup_suffix);
60 tmp_file = strdup(file);
63 base_versions = concat(basename(tmp_file), ".~");
65 if (base_versions == NULL)
67 tmp_file = strdup(file);
68 if (tmp_file == NULL) {
72 dir = dirname(tmp_file);
78 highest_backup = max_backup_version(base_versions, dir);
81 if (backup_type == numbered_existing && highest_backup == 0)
82 return concat(file, simple_backup_suffix);
83 return make_version_name(file, highest_backup + 1);
87 * Return the number of the highest-numbered backup file for file FILE in
88 * directory DIR. If there are no numbered backups of FILE in DIR, or an
89 * error occurs reading DIR, return 0. FILE should already have ".~" appended
93 max_backup_version(const char *file, const char *dir)
97 int highest_version, this_version;
98 size_t file_name_length;
105 file_name_length = strlen(file);
107 while ((dp = readdir(dirp)) != NULL) {
108 if (dp->d_namlen <= file_name_length)
111 this_version = version_number(file, dp->d_name, file_name_length);
112 if (this_version > highest_version)
113 highest_version = this_version;
116 return highest_version;
120 * Return a string, allocated with malloc, containing "FILE.~VERSION~".
121 * Return 0 if out of memory.
124 make_version_name(const char *file, int version)
128 if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
134 * If BACKUP is a numbered backup of BASE, return its version number;
135 * otherwise return 0. BASE_LENGTH is the length of BASE. BASE should
136 * already have ".~" appended to it.
139 version_number(const char *base, const char *backup, size_t base_length)
145 if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
146 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
147 version = version * 10 + *p - '0';
148 if (p[0] != '~' || p[1])
155 * Return the newly-allocated concatenation of STR1 and STR2. If out of
159 concat(const char *str1, const char *str2)
163 if (asprintf(&newstr, "%s%s", str1, str2) == -1)
169 * If ARG is an unambiguous match for an element of the null-terminated array
170 * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
171 * does not match any element or -2 if it is ambiguous (is a prefix of more
175 argmatch(const char *arg, const char **optlist)
177 int i; /* Temporary index in OPTLIST. */
178 size_t arglen; /* Length of ARG. */
179 int matchind = -1; /* Index of first nonexact match. */
180 int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */
182 arglen = strlen(arg);
184 /* Test all elements for either exact match or abbreviated matches. */
185 for (i = 0; optlist[i]; i++) {
186 if (!strncmp(optlist[i], arg, arglen)) {
187 if (strlen(optlist[i]) == arglen)
188 /* Exact match found. */
190 else if (matchind == -1)
191 /* First nonexact match found. */
194 /* Second nonexact match found. */
205 * Error reporting for argmatch. KIND is a description of the type of entity
206 * that was being matched. VALUE is the invalid value that was given. PROBLEM
207 * is the return value from argmatch.
210 invalid_arg(const char *kind, const char *value, int problem)
212 fprintf(stderr, "patch: ");
214 fprintf(stderr, "invalid");
215 else /* Assume -2. */
216 fprintf(stderr, "ambiguous");
217 fprintf(stderr, " %s `%s'\n", kind, value);
220 static const char *backup_args[] = {
221 "none", "never", "simple", "nil", "existing", "t", "numbered", 0
224 static enum backup_type backup_types[] = {
225 none, simple, simple, numbered_existing,
226 numbered_existing, numbered, numbered
230 * Return the type of backup indicated by VERSION. Unique abbreviations are
234 get_version(const char *version)
238 if (version == NULL || *version == '\0')
239 return numbered_existing;
240 i = argmatch(version, backup_args);
242 return backup_types[i];
243 invalid_arg("version control type", version, i);